As is well-known, in a vehicle, a suspension spring is interposed between a vehicle body and an axle so as to elastically support the vehicle body. With this configuration, even if wheels are vibrated due to roughness of a road surface during running of the vehicle, it is possible to prevent the vibration from being transmitted directly to the vehicle body.
Further, the vibration cannot be damped only with use of the suspension spring, and resonance may occur depending on a vibration frequency. Therefore, a damper is provided in parallel to the suspension spring.
Japanese Utility Model Application Laid-open No. 63-159307 and Japanese Utility Model Application Laid-open No. 07-038776 disclose, as a damper installed in a straddle-type vehicle such as a motorcycle, a damper with a vehicle height adjusting function, which is capable of adjusting a vehicle height in accordance with a physique of a user.
For example, as illustrated in FIGS. 4A and 4B, the damper with a vehicle height adjusting function includes a cylinder 4, a rod 5 inserted into the cylinder 4 so as to be capable of protruding from and retracting into the cylinder 4, a rod-side mounted member 1A fixed to an upper end of the rod 5 illustrated in FIG. 4A, and a cylinder-side mounted member 8 fixed to a lower end of the cylinder 4 illustrated in FIG. 4A.
A vehicle-body-side mounting portion C1 is formed in the rod-side mounted member 1A, and an axle-side mounting portion C2 is formed in the cylinder-side mounted member 8. The damper is interposed through the intermediation of the mounting portions C1, C2 between a frame on the vehicle body side and a swing arm on the axle side.
The damper further includes a vehicle height adjusting mechanism H1 capable of adjusting a distance X between the mounting portions C1, C2. The vehicle height adjusting mechanism H1 includes a holder 2A fixed to the upper end of the rod 5 illustrated in FIG. 4A, and a shaft portion 100 formed in the rod-side mounted member 1A and threadingly engaged with the holder 2A. The rod-side mounted member 1A is turned relative to the holder 2A to change an overlapping amount between the shaft portion 100 and the holder 2A. Thus, the vehicle height can be adjusted.
In other words, the overlapping amount between the shaft portion 100 and the holder 2A is increased, specifically, an axial length Y of a region in which the shaft portion 100 and the holder 2A overlap each other is increased, and thus the distance X between the mounting portions C1, C2 is correspondingly reduced. As a result, it is possible to lower the vehicle height.
On the other hand, the overlapping amount between the shaft portion 100 and the holder 2A is reduced, specifically, the axial length Y of the region in which the shaft portion 100 and the holder 2A overlap each other is reduced, and thus the distance X between the mounting portions C1, C2 is correspondingly increased. As a result, it is possible to raise the vehicle height.